Arthroscopic lateral portals revisited. A cadaveric study of the safe zones.

Lateral knee portal placement is defined by and divided into five anatomic zones (A through E) beginning just anterolateral to the patellar ligament and proceeding posteriorly at 1-cm intervals. The arthroscopic anatomy and the open dissected lateral knee anatomy are correlated in this study with a fresh frozen cadaver. Zone A includes the anterolateral capsulosynovial layer and zone B includes the anterolateral capsulosynovial layer, anterior portion of the iliotibial tract, and the patellotibial ligament. The lateral capsulosynovial layer and the middle-to-posterior portion of the iliotibial tract comprise zone C. Zone D includes the lateral collateral ligament, the popliteal tendon, and the anterior border of the long head of the biceps femoris tendon. The mid-portion of the long head of the biceps femoris tendon and the peroneal nerve make up zone E. Structures penetrated are defined as safe in zones A, B, and C, and unsafe in zone E. Structures that are potentially penetrable are defined as relatively at risk in zone D. When placing a portal for arthroscopic visualization of the posterolateral compartment of the knee, the placement should be between zone D and the anterior portion of zone E at 90 degrees of knee flexion. This potential space is between the lateral collateral ligament and the anterior portion of the biceps femoris tendon; it enlarges with increasing knee flexion and allows for easier portal placement.